William H. Ray Jr. of Towson, Md., who was already in custody on an unrelated matter, was charged with murder, robbery and conspiracy to commit robbery, Park said.

The elder Prassos was fatally wounded in the abdomen when he struggled with the gunman, police said.

Park said a tip through a "crime stoppers" program led police to place Ray under surveillance. Then, Park said, investigators developed evidence that Ray may have been in touch with the younger Prassos days before the robbery occurred, the morning of the robbery and then days later.

Park said the gunman seemed to have some detailed knowledge of the restaurant, entering by the kitchen door when it was unlocked on the morning in question, a Sunday. The gunman apparently proceeded directly to the office where the elder Prassos was, Park said.

Family members and friends have continued to operate the restaurant, and it was there that Dimitrios Prassos was arrested about 4 p.m. yesterday, police said.

One restaurant employe, who said her name was Cathy, said Dimitrios Prassos had once worked for his father in the restaurant but had quit before the robbery. She said the younger Prassos has not been actively involved in the efforts to keep the business going after George Prassos' death.

Ray was already incarcerated at the Maryland Reception and Diagnostic Center in Baltimore, beginning a one-year sentence for driving while intoxicated, when he was arrested in the slaying, Park said.